E: Unable to correct problems, you have held broken packages-之apt-get 下载报依赖问题

root@VM_0_10:~# apt-get install zabbix-agent
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 zabbix-agent : Depends: libcurl3 (>= 7.16.2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

apt install aptitude

aptitude install  -y zabbix-agent

#然后就成功了
 有的问题 apt-get 解决不了，必须使用 aptitude 解决，有的问题，用 aptitude 解决不了，必须使用apt-get.

    aptitude 解决得更好的地方： install, remove, reinstall（apt-get无此功能）, show（apt-get无此功能）, search（apt-get无此功能）, hold（apt-get无此功能）, unhold（apt-get无此功能）,

    apt-get 解决得更好的地方： source（aptitude无此功能）, build-dep （低版本的aptitude没有build-dep功能）

    apt-get 跟 aptitude 没什么区别的地方：update, upgrade (apt-get upgrade=aptitude safe-upgrade, apt-get dist-upgrade=aptitude full-upgrgade)